1. Field of the Invention
The present invention relates to the field of automatic adjustment system for adjusting electrical variable techniques, more specifically to a circuit for reducing energy-consumption in protection state, and in particular to a protection circuit with low energy-consumption and driving circuit thereof.
2. The Related Arts
The known LED backlight driving circuit is shown in FIG. 1. When a detection circuit (LED constant-current driving IC) detects abnormal current and voltage in the LED string, a protection mechanism will be activated to stop outputting driving signals to the MOS transistor Q1. The MOS transistor Q1 is then in the turned off state so that the entire circuit loses the boosting function. At this point, the output voltage equals to the input voltage and the LED string is turned off because of insufficient voltage. However, even the entire circuit is in a protection state and the LED string is turned off, the input voltage still exists, which leads to energy-consumption in peripheral small-signal circuit and voltage-dividing resistors and causes unnecessary consumption drawback.
China Application No. 201210317379.X and Publication No. CN 102842893A, titled “LED light bar short-circuit protection control circuit,” disclosed an LED light bar short-circuit protection control circuit, comprising an LED constant-current sampling control circuit, connected in the power supply loop of the LED light bar to realize constant-current control; a switch circuit, connected in the power supply loop of the LED light bar and disposed between the LED light bar and power supply, with control terminal of the switch circuit connected to the backlight control signal; an LED short-circuit protection circuit, connected between the LED constant-current sampling control circuit and the control terminal of the switch circuit, and comprising: a comparator, with non-inverting input terminal connected to the LED constant-current sampling control circuit and inverting input terminal connected to a default threshold signal, when the signal at the non-inverting input terminal of the comparator has a greater value than the signal at the default threshold signal, the LED short-circuit protection circuit outputting a control signal to the control terminal of the switch circuit and the switch circuit cutting off the power supply to the LED light bar. Although the LED light bar short-circuit protection control circuit can perform detection and protection control on the LED short-circuit behavior, the protection control circuit achieves the objective by employing the mechanism of cutting off the entire power supply to the LED light bar. The mechanism is equivalent to the effect that during the short-circuit protection control process, the power supply to the overall circuit must be cut off and turned on again, which leads to response delay of the overall power supply circuit and reduces the lifespan of the components of the circuit, and causes the drawbacks of low efficiency and effects of the overall circuit.
China Application No. ZL200820301509.X and Publication No. CN 201229514Y, titled “low energy-consumption circuit of series regulator and overcurrent protection,” disclosed a low energy-consumption circuit of series regulator and overcurrent protection, comprising an adjustment circuit and a current sampling circuit. The adjustment circuit and the current sampling circuit are serially connected between the input terminal and the output terminal. The one end of the current sampling circuit connected to the output terminal is connected to the common terminal through the output voltage sampling circuit. The sampling voltage of the adjustment circuit is connected to the inverting input terminal of the comparator circuit and the non-inverting input terminal of the comparator circuit is connected to the output voltage sampling circuit. The output terminal of the comparator circuit is connected to the control terminal of the adjustment circuit. The sampling voltage of the output voltage sampling circuit is connected to the control terminal of the adjustment circuit. The negative terminal of the adjustment circuit is connected to the common terminal and the positive terminal of the adjustment circuit is connected to the control terminal of the adjustment circuit. The two ends of the adjustment circuit are connected to activation circuit. The control terminal of the adjustment circuit is connected to an over-bias power supply through an over-bias current-limiting circuit. Although the disclosed circuit can achieve the object of controlling output current in the case of over-current or short-circuit, the problem solved by the disclosed circuit is to enable long-term operation in case of short-circuit and automatic restoring power supply after the short-circuit or over-current situation is eliminated. In addition, the disclosed circuit is still to dispose adjustment circuit in the overall circuit structure, and the aforementioned drawbacks of response delay of the overall power supply circuit and reducing lifespan of the components of the circuit, as well as causing the drawbacks of low efficiency and effects of the overall circuit remain.
In summary, the known protection circuit for over-current or short-circuit with low energy-consumption, when applied to the current LED circuit, is mostly disposing adjustment circuit or control switch circuit in the overall circuit structure, which only realizes limited function of performing short-circuit detection and protection control on LED, without completely solve the drawbacks of response delay of the overall power supply circuit and reducing lifespan of the components of the circuit, as well as causing the drawbacks of low efficiency and effects of the overall circuit.